New generation optical fiber transmission test
Hideki Furukawa, director of the Photonic Network System Research Office of Japan's Institute of Information and Communication (NICT, a subsidiary of Japan's Ministry of Internal Affairs and Communications, which means "information" in Japanese), pointed out that "if the traffic volume continues to increase, it will exceed the current limit of optical fiber in the 2020s", which sounded the alarm for the relevant situation. According to the statistics of the Ministry of Internal Affairs and Communications of Japan, the domestic communication volume in Japan increased to more than 10 times during 10 years.
The reason is that there are more and more opportunities to use smart phones and personal computers. With the improvement of the performance of these terminal products, video has also become the object of mutual transmission. When transmitting information, digital signals carrying information will be converted into optical signals and transmitted through optical cables. Optical fiber is spread all over the world in the form of submarine optical cable, which has become an indispensable existence for communication with the world. It can be said that optical fiber is the "behind-the-scenes hero" supporting modern society.
The current optical fiber (left) has 1 optical signal channels, but the new generation optical fiber (right) will have multiple optical signal channels (picture provided by Japan Institute of Information and Communication).
In the past, the transmission capacity of each optical fiber was increasing to cope with the increase in traffic. In 2005, the transmission capacity was 1 trillion bits per second, and now it has reached more than ten trillion bits.
However, the current optical fiber can only increase the transmission capacity to 100 megabit. If more information is transmitted, the laser used for communication will be too strong, and there is a risk that the optical fiber will melt. If the threat becomes a reality, communication will be stagnant, which will have an impact on business efficiency and labor model reform.
According to the forecast of Japan Electronic Information Technology Industry Association, the global communication volume is expected to increase to 10/5 times in 2030, and will continue to increase in the future. In order to solve this problem, optical fiber enterprises at home and abroad in Japan are promoting the development of a new generation of optical fiber called "multi-core".
In the past, optical fiber had only one optical signal channel called "core", and multi-core fiber would have three 4 cores. Just as with the increase of the number of lanes on the road, the number of vehicles that can drive will also increase. If there are more channels for optical signals, the transmission capacity will also increase several times.
In addition, in order to accurately transmit optical signals, it is necessary to avoid interference from other signals, but the diameter of an optical fiber is only 0. 1.25 mm, which is similar to the thickness of hair. Therefore, the spacing between fiber cores is only about 0.05 mm, which interferes with the optical signals leaked from adjacent fiber cores.
One of the solutions is to add a low refractive index glass layer around the fiber core as a material to avoid leakage to the surrounding area. By adding fluorine to the glass, only the refractive index of the peripheral part decreases, and the optical signal remains in the core.
In March, Japan Institute of Information and Communication conducted a transmission experiment with a four-core optical fiber, and successfully realized the transmission of 6 10 trillion bits per second. It has set a world record for the transmission capacity of optical fiber with the same thickness. In this way, even if there are multiple cores, the thickness of the optical fiber will not change.
Multi-core optical fiber can be used with existing optical fiber, so it is considered that it will be gradually replaced.
Sumitomo Electric Industry of Japan laid multi-core optical fiber in Italy for the first time in the world in 20 19, and Japanese information and communication research institutions gave positive comments on the related performance. According to Japan's "Institute of Electronic Information and Communication", from around 2025, four-core optical fibers will be used in short-distance communication networks below 10 km. It is expected to be applied to submarine optical cables around 2030.
In order to further improve the performance of each optical fiber, another method is to develop a "multimode" optical fiber, which makes the core thicker and allows optical signals to pass through multiple channels in 1 core. The practical application of multi-core combination is considered to wait until the second half of 2030.
In the field of new generation optical fiber, Japanese companies are ahead in research and development. According to the report released by Japan Patent Office on 20 18, in the field of multi-core optical fiber, the top four patent applications in the world are Fujikura, Sumitomo Electric, NTT and Furukawa Electric Industry, which are monopolized by Japanese companies. In the multimode field, the 24th place is also monopolized by Japanese companies such as NTT, Sumitomo Electric and Fujikura. Fujikura plans to commercialize multi-core optical fiber in the mid-2020s.
Of course, companies outside Japan are also promoting the development of a new generation of optical fibers. Corning, an American special glass manufacturer, ranks 1 in the number of patents for multimode optical fibers, and has also successfully achieved large-capacity transmission in the multi-core field. Italy's Presman Group also has the research results of a new generation of optical fiber. Like smart phones and base stations, the global competition of optical fiber may become more and more fierce.
Do you think the role of optical fiber is important in the 5G era?